Just days after voting to leave the European Union, more than 2.5 million Britons and UK residents had signed a petition calling for a second vote, forcing lawmakers to at least consider a debate on the issue.

Parliament has to consider a debate on any petition posted on its website that attracts more than 100,000 signatures.

The proposal, posted before the June 23 referendum, said the government should hold another plebiscite on EU membership if the support for Leave or Remain in a referendum was less than 60 percent in a turnout of under 75 percent of eligible voters.

The result on Thursday saw 52 percent of voters, 17,410,742 people, back a British exit, on a turnout of 72 percent.

According to an opinion poll conducted on Friday, half of voters said the result should stand, even if the EU offered more reforms to Britain's EU membership, while 39 percent said a second referendum should be held under the new terms offered.

Some 48 percent of British adults said they were happy with the result against 43 percent who were unhappy, according to the poll by ComRes for the Sunday Mirror.

The online petition -- which only British citizens or UK residents have the right to sign -- was proving so popular that by 2136 GMT on Saturday, 2,503,065 people had signed it.

Most of those who signed were based in areas where support for staying in the EU was strongest, most especially London, the website indicated.

Prime Minister David Cameron, who said on Friday he would resign after leading the failed campaign to keep Britain in the EU, had said there would be no second referendum.

The ComRes poll also asked a representative sample of 1,069 adults when the next general election should be.

One third said there should be a vote as soon as the next prime minister was in place in the autumn, while 23 percent said an election should be held early next year.

Some 27 percent said the next election should be in 2020 as currently planned, according to the online poll.